It is highly desirable to provide copper base alloys with a good combination of strength and bend properties, particularly while retaining the other advantageous properties of these alloys.
The usefulness of sheet materials is often limited by their ability to be formed by bending into the desired shape. This is particularly true when cold rolling is employed in order to strengthen the strip material since the cold working reduces bend ductility. In addition, cold rolling also leads to anisotropy in bend behavior where a lower bend ductility is observed when measured with the bend axis parallel to the rolling direction, that is, when the bend ductility is measured with the bend axis 0.degree. to the rolling direction. Thus, the most desirable combination of properties is extremely difficult to achieve, that is, high bend ductility without anisotropy combined with high strength properties.
Cold rolling of copper base alloys having a low stacking fault energy promotes an unfavorable deformation texture in the alloy and this texture contributes to anisotropy in mechanical properties, including bend ductility. The intensity and the characteristics of the deformation texture are described by the plastic strain ratio R measured at 0.degree., 45.degree. and 90.degree. to the rolling direction.
Accordingly, it is a principal object of the present invention to provide a process for obtaining a combination of good strength and good bend properties in copper base alloys having low stacking fault energy.
It is a still further object of the present invention to provide a process as aforesaid which is convenient to use on a commercial scale and which allows the retention of other desirable properties in these alloys.
It is a particular object of the present invention to provide a process as aforesaid which enables one to obtain high bend ductility without anisotropy combined with good strength properties.
Further objects and advantages of the present invention will appear from the ensuing specification.